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Build a Counter component

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01

Understand the problem

Build a counter with increment, decrement and reset buttons.

ReactStateEvents
02

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03

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Building a Counter in React

Mental model: A counter is the simplest controlled component — the value lives in the parent and the counter only emits requests to change it. Add min/max/step clamping plus disabled-edge logic and it becomes a genuinely reusable primitive instead of a useState(0) toy.

Solution ready — 2 min read

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04

React solution

Complete solutionRun Playground
import React, { useState } from 'react';
import Counter from './src/Counter';

export default function App() {
  const [count, setCount] = useState(0);
  return (
    <div style={{ fontFamily: 'sans-serif', padding: 20 }}>
      <h1>Counter Demo</h1>
      <Counter value={count} onChange={setCount} min={0} max={10} step={1} />
      <p style={{ marginTop: 16, fontSize: 18 }}>
        Current value: <strong>{count}</strong>
      </p>
    </div>
  );
}
05

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Transmission complete // awaiting log

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Dossier 4 of 87 decoded in the Frontend Machine Coding track. One more won't hurt.

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